The search giant continued to make less money — a 16 percent decline in costs per click — from each online ad, but made it up on volume as a 42 percent jump in ad inventory helped lead to higher revenues.

While discussing second-quarter results with analysts yesterday, Google executives tried to make light of the situation, saying it wouldn’t be an earnings call without a costs-per-click story.

Some on Wall Street weren’t amused.

“It’s a problem.” said analyst Colin Gillis with BGC Partners. “You have ever-expanding inventory, but people are paying less for it. It’s a horrible trend.”

The decline in ad dollars per click is accelerating, and last quarter that measure was down 12 percent, and it was down 8 percent the prior quarter.

The company has blamed the decline on the consumer shift to mobile, where ads are generating less money.

Still, Google’s overall revenue was up 35 percent in the period, to $12.2 billion, helped by the $12.5 billion acquisition of Motorola Mobility in May.

Motorola brought in $1.25 billion in new revenue for Google, but hurt the search company’s bottom line.

Profit margins are much less for manufacturing hardware than for search. In fact, Motorola posted a loss of $233 million in the period, while Google’s core business rang the cash register with a profit of $3.4 billion.

The second-quarter results showed just how much the transition to a hardware maker will eat into Google’s money, with costs more than doubling.

Still, at $10.12 earnings per share, Google beat Wall Street’s expectations, and fueled an after-hours rally, when the stock rose more than 3 percent to more than $611.